From 39b4c0d686389c2a0eeb249b5c0d6ae1626b989b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20Kr=C3=BCger?= <mkg20001@gmail.com>
Date: Tue, 20 Feb 2024 23:12:41 +0100
Subject: [PATCH 1/2] nixos/lxc-container: link to prepare-root when
 boot.initrd.systemd.enable is on

Previously we were doing some parts like activation in the init script,
so linking to that works for non-systemd init

With boot.initrd.systemd.enable we no longer run activation in the init script,
but instead a new script named prepare-root, which is used instead.
---
 nixos/modules/virtualisation/lxc-container.nix | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/nixos/modules/virtualisation/lxc-container.nix b/nixos/modules/virtualisation/lxc-container.nix
index 8d3a480e6dc8..95e3083ff9ed 100644
--- a/nixos/modules/virtualisation/lxc-container.nix
+++ b/nixos/modules/virtualisation/lxc-container.nix
@@ -14,7 +14,9 @@
 
   options = { };
 
-  config = {
+  config = let
+    initScript = if config.boot.initrd.systemd.enable then "prepare-root" else "init";
+  in {
     boot.isContainer = true;
     boot.postBootCommands =
       ''
@@ -41,7 +43,7 @@
 
       contents = [
         {
-          source = config.system.build.toplevel + "/init";
+          source = config.system.build.toplevel + "/${initScript}";
           target = "/sbin/init";
         }
         # Technically this is not required for lxc, but having also make this configuration work with systemd-nspawn.
@@ -65,7 +67,7 @@
 
       pseudoFiles = [
         "/sbin d 0755 0 0"
-        "/sbin/init s 0555 0 0 ${config.system.build.toplevel}/init"
+        "/sbin/init s 0555 0 0 ${config.system.build.toplevel}/${initScript}"
         "/dev d 0755 0 0"
         "/proc d 0555 0 0"
         "/sys d 0555 0 0"
@@ -74,7 +76,7 @@
 
     system.build.installBootLoader = pkgs.writeScript "install-lxd-sbin-init.sh" ''
       #!${pkgs.runtimeShell}
-      ${pkgs.coreutils}/bin/ln -fs "$1/init" /sbin/init
+      ${pkgs.coreutils}/bin/ln -fs "$1/${initScript}" /sbin/init
     '';
 
     # networkd depends on this, but systemd module disables this for containers
@@ -83,7 +85,7 @@
     systemd.packages = [ pkgs.distrobuilder.generator ];
 
     system.activationScripts.installInitScript = lib.mkForce ''
-      ln -fs $systemConfig/init /sbin/init
+      ln -fs $systemConfig/${initScript} /sbin/init
     '';
   };
 }

From c607e70f7053e96e21b045fe1f47c57356c96341 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20Kr=C3=BCger?= <mkg20001@gmail.com>
Date: Tue, 20 Feb 2024 23:42:59 +0100
Subject: [PATCH 2/2] nixosTests.incus: add test with old and new init

---
 nixos/tests/incus/container.nix | 4 ++--
 nixos/tests/incus/default.nix   | 6 +++++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/nixos/tests/incus/container.nix b/nixos/tests/incus/container.nix
index 0e65cc1e1529..0f42d16f133d 100644
--- a/nixos/tests/incus/container.nix
+++ b/nixos/tests/incus/container.nix
@@ -1,11 +1,11 @@
-import ../make-test-python.nix ({ pkgs, lib, ... } :
+import ../make-test-python.nix ({ pkgs, lib, extra ? {}, ... } :
 
 let
   releases = import ../../release.nix {
     configuration = {
       # Building documentation makes the test unnecessarily take a longer time:
       documentation.enable = lib.mkForce false;
-    };
+    } // extra;
   };
 
   container-image-metadata = releases.lxdContainerMeta.${pkgs.stdenv.hostPlatform.system};
diff --git a/nixos/tests/incus/default.nix b/nixos/tests/incus/default.nix
index c8e53774599b..ff36fe9d6730 100644
--- a/nixos/tests/incus/default.nix
+++ b/nixos/tests/incus/default.nix
@@ -5,7 +5,11 @@
   handleTestOn,
 }:
 {
-  container = import ./container.nix { inherit system pkgs; };
+  container-old-init = import ./container.nix { inherit system pkgs; };
+  container-new-init = import ./container.nix { inherit system pkgs; extra = {
+    # Enable new systemd init
+    boot.initrd.systemd.enable = true;
+  }; };
   lxd-to-incus = import ./lxd-to-incus.nix { inherit system pkgs; };
   preseed = import ./preseed.nix { inherit system pkgs; };
   socket-activated = import ./socket-activated.nix { inherit system pkgs; };